Lubricating greases containing metal salts of nu-alkanoyl-sulfanilic acids



United States Patent O 2,987,477 LUBRICATING GREASES CONTAINING METAL SALTS F N-ALKANOYL-SULFANILIC ACIDS Norman R. Odell, Fishkill, and Joseph F. Lyons,

Poughkeepsie, N.Y., assignors to Texaco Inc., a corporation of Delaware No Drawing. Filed Dec. 29, 1958, Ser. No. 783,133 7 Claims. (Cl. 252-33) This invention relates to a novel class of grease thickening agents and to lubricating greases containing these compounds. More particularly, it relates to lubricating greases thickened with metal salts of N-alkanoyl-sulfanilic acids.

The N-alkanoyl-sulfanilic acid metal salts are represented by the formula wherein R is an aliphatic hydrocarbon group, M is a metal, such as sodium, potassium, lithium, calcium, barium, strontium, zinc, aluminum, tin, cadium, iron manganese, etc., and n is an integer equal to the valence of M. The preferred compounds of this class are those wherein R contains from 1 to about 30 carbon atoms, most suitably from about 8 to about 22 carbon atoms, and M is a metal of the group consisting of alkali metals, alkaline earth metals, aluminum and zinc.

We have found that the above compounds constitute a very valuable class of grease thickening agents. Greases thickened with these compounds, are characterized by a combination of desirable lubricating properties, including high dropping points, good shear stability and excellent water resistance properties, not obtainable with the conventional thickening agents.

The N-alkanoyl-sulfanilic acid salts are readily obtained by reacting acyl chlorides and sulfanilic acid in the presence of a solvent such as pyridine, and then converting the reaction products into the metal salts by reaction with suitable basic metal compounds in the conventional manner.

The greases of this invention comprise essentially oleaginous liquids admixed with metal salts of the above class in suificient amounts to thicken the oleaginous liquids to a grease consistency. Ordinarily, the composition will contain from about to about 45 percent by Weight of the thickening agent, and preferably from about 10 to about 35 percent by weight of the metal compound based on the weight of the composition.

The oleaginous liquids employed in these greases may be any oils of lubricating characteristics which are suitable for use in the conventional soap thickened greases. They include particularly the conventional mineral oils in the lubricating oil viscosity range, having viscosities from about 80 seconds Saybolt Universal at 100 F. to about 225 seconds Saybolt Universal at 210 F., which may be either distillate or residual fractions, and parafdnic or naphthenic in character. The preferred mineral oils are those having viscosities in the range of from about 300 seconds to about 600 seconds Saybolt Universal at 100 R, which may be blends of difierent oils, including oils of lighter and heavier viscosities. For special purposes, such as for producing wide temperature range greases, synthetic oils, such as polyethers, polyesters, silicone oils, etc. may be employed as part or all of the oleaginous liquid component. Suitable polyesters include the aliphatic dicarboxylic acid diesters such as di-Z-ethylhexyl sebacate, di(secondary amyl)sebacate, di-Z-ethylhexyl azelate, di-isooctyl adipate, eac., and also the reaction products of dicarboxylic acids with glycols, disclosed in U.S. 2,628,974. Suitable silicone oils are described, for example, in U.S. 2,410,346 and U.S. 2,469,-

- Patented June 6, 1961 888. The methylchlorophenylsilicone oils, containing at least about 3 percent by weight of chlorine, and ordinarily about 4-12 percent by weight of chlorine, are regarded as the preferred silicone oils for use in the greases of this invention.

Additives of the usual types employed in lubricating greases may be employed in these greases also, including oxidation inhibitors, rust and corrosion inhibitors, extreme pressure agents, etc. A very suitable class of oxidation inhibitors are those of the amine type, including for example, diphenylamine, alphaand beta-napthylamines, diphenyl p phenylenediamine, and polymerized dihydroquinolines, such as 2,2,4-trimethyl-l,2-dihydroquinoline, which is sold commercially under the trade name of Agerite Resin D. Such materials may be employed in minor amounts, such as from about 0.05 to about 10 percent by weight, and preferably in amounts from about 0.5 to about 5 percent by weight of the grease composition. 1

The grease preparation may be carried out by merely mixing together the preformed metal salt with the lubricating oil and any additives employed in the grease, employing any convenient means such as milling in a colloid mill or a paint mill to obtain a thorough dispersion of the thickening agent in the oleaginous liquid. The preparation may also be carried out by an in situ method if desired, wherein the sulfanilic acid compound is neutralized by means of a basic metal compound in the presence of at least a portion of the lubricating oil employed in the grease.

The following examples are given for the purpose of more fully disclosing the invention.

Example] A lubricating grease having the following composition in percent by weight:

Calcium N-stearoyl sulfanilate 17.3 Lubricating oil 81.3

The N-stearoyl sulfanilic acid employed as the saponifiable material in this grease preparationis obtained in the following manner: 600 milliliters of pyridine and 115 grams of sulfanilic acid are added to a solution of 292 grams of stearoyl chloride in 600 milliliters of benzene.

becomes transparent at -95" C. and melts completely.

at 200 C.

The lubricating oil-is a refined naphthenic distillate oil. having a Saybolt Universal viscosity at F. of about" 315 seconds.

The grease preparation is carried out in the following manner: A reaction mixture consisting of 109 grams of N-stearoyl sulfanilic acid obtained as described above, 550 grams of water, 131 grams of mineral lubricating oil and 14.1 grams of lime is heated at l80-l90 F. for 2 hours with stirring. The mixture is then further heated to 450-452 F., maintained at that temperature for about 10 minutes, and then cooled with continued stirring at a rate of about 2 F. per minute. When the mixture has cooled to 341 F. an additional 323 grams of lubricating oil is added gradually. The grease mixture is drawn at 200 F., and finished by milling with 2 passes through a Premier colloid mill at 0.002 inch clearance.

A smooth N. L. G. I. No. 0 grade grease of buttery texture is obtained as described above, having a very high dropping point for a calcium base grea'se, above 500 F., together with good shear stability and excellent water resistance properties.

The sodium N-stearoyl-sulfanilate is prepared from the N-stearoyl-sulfanilic acid obtained as described in Example I. The acid is converted to the sodium salt by reacting it with sodium hydroxide in aqueous solution, employing a slight excess of sodium hydroxide. The salt formed is filtered, washed with water until the washings are neutral and dried in air.

The lubricating oil is a blend in a 3:1 ratio by weight of a refined residual oil having a viscosity of 120 seconds Saybolt Universal at 210 F. from a paraflin base crude and a refined paraflinic distillate oil having a Saybolt Universal viscosity at 100 F. of about 335 seconds.

The grease preparation is carried out in the following manner: 225 grams of sodium N-stearoyl sulfanilate, 500 grams of water and 360 grams of the oil blend are charged to the grease kettle and the mixture heated at 180-190 F. for 2 hours. The mass is then further heated at 300-310 F. for 2 hours, and cooled to about 203 F. at a rate of about 0.5 F. per minute while adding an additiona1 506 grams of the oil blend. When the grease mixture is at about 224 F., 34 grams of Agerite Resin D are added. The grease is finished by milling with 3 passes through a Premier colloid mill at 0.002 inch clearance.

A smooth N. L. G. I. No. grade grease of buttery texture is obtained as described above, having a combination of excellent lubricating properties as shown by the following results obtained upon this grease in standard tests:

Shear stability test, ASTM worker:

Penetration at 77 F. (M; cone)- Example III Lubricating grease having the following composition in percent by weight:

Zinc Nlauroyl sulfanilate 30.0 Formamide 0.5 Lubricating oil 69.5

' The zinc N-lauroyl sulfanilate is obtained by reacting sulfanilic acid and lauroyl chloride under the conditions described in Example I and then converting the reaction product to the zinc salt by treating it in aqueous solution 4 with zinc acetate in a mol ratio with the sulfanilic acid compound of about 1:2, respectively, employing a slight excess of the zinc acetate.

The lubricating oil is a blend of di-2-ethylhexyl sebacate and a refined paraifinic distillate oil having a Saybolt Universal viscosity at 100 F. of about 100 seconds in a ratio of 3:1, respectively, by weight;

The grease preparation is carried out substantially. as

described in Example H.

A smooth N. L. G. I. No. 2 grade greaseis obtained as described above having a dropping point above 500 F. and good shear resistance and water stability substantially equivalent to those of the grease of Example I.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating grease consisting essentially of a lubricating oil thickened to a grease consistency with a compound represented by the formula wherein R is an aliphatic hydrocarbon group containing from 8 to about 22 carbon atoms, M is a metal selected from the group consisting of alkali metals, alkaline earth metals, aluminum and zinc and n is an integer equal to the valence of the said metal.

2. The composition according to claim 1 wherein M is sodium.

3. The composition according to claim 1 wherein M is calcium.

4. The composition according to claim 1 wherein R contains from about 11 to about 17 carbon atoms.

5. The composition according to claim 1 wherein the said lubricating oil is a mineral oil.

6. A lubricating grease consisting essentially of a lubricating oil thickened to a grease consistency with calcium N-stearoyl sulfanilate.

7. A lubricating grease consisting essentially of a lubricating oil thickened to a grease consistency with sodium N-stearoyl sulfanilate.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,970 Zimmer et a1. July 13, 1948 2,483,800 Zimmer et al. Oct. 4, 1949 2,535,101 Sproule et a1. Dec. 26, 1950 2,620,301 McLeod Dec. 2, 1952 2,854,408 Brugmann et a1. Sept. 30, 1958 FOREIGN PATENTS 502,723 Canada May 18, 1954 M t 41 m 

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A COMPOUND REPRESENTED BY THE FORMULA 